I wrote down on a piece of paper all the bad/hurtful things he had done so when I missed him I would remind myself of the dealbreakers. I carried around the little card in my purse.
I have a similar card taped under my computer keyboard at work. I look at it when I obsess. My support group counselor said when we get the urge write them a letter we will never send instead, Ive dont that so many times and surprisingly it alwaysturns to angry, not what I expected but it helped me grow and helped limit the obsession. Still comes from time to time, heck I had to get a copy of recent arrest report for disorderly intox who knows it may help in my custody case someday.
But I will promise the less you give into those obsesions, the easier it gets, the less it hurts and soon the less they even come tome mind